Coleman, who played lesbian Jasmine Thomas in the Yorkshire soap, starts filming in May and will make her first appearance in the Christmas Day special.

Fans will see six episodes this year with eight more in 2013 and Moffat revealed Gillan would be written out in the fifth episode of 2012 in a "final encounter" with the weeping angels: "Not everyone gets out alive and I mean it this time."

Coleman, from Blackpool, will soon appear as Annie Desmond in Julian Fellowes' new ITV1 Titanic drama.

Jenna-Louise Coleman in London as she is unveiled as the new Dr Who assistant. Credit: Gareth Fuller/PA Wire

She said she was "beyond excited" to join the show and "so relieved" to finally be able to tell people she had the job six weeks after finding out:

"I was in Marks and Spencer holding an avocado deciding what goes best in a salmon salad, that was my big debate at the time, and then I got the phone call and just had to put everything down and leave the shop and go for a walk.

"I told my mum but I couldn't tell anyone else so I was this weird excited but had to act completely normal."

"Working with Matt it felt so spontaneous, and we just didn't know where it was going to go and he's got so much energy that's its just infectious, so that's what I feel excited about."